First House Speaker invited Netanyahu to speak before Congress, which might be unconstitutional (what do these people Washington and Jefferson know about the Constitution anyway):
As described in The Executive Power over Foreign Affairs, George Washington as President asserted his role as the “sole channel of official intercourse” with foreign nations. (Letter from Washington to the Emperor of Morocco, Dec. 1, 1789, cited at 111 Yale L.J., p. 317; further discussion of the point at pp. 318-322). Notably, Washington quarreled with French ambassador Edmond Genet in 1793, who sought to enlist U.S. support for France in its conflict with Britain. When Washington insisted on neutrality, Genet attempted to communicate directly with Congress, which he suspected was more sympathetic to France than the President. Washington, through Secretary of State Thomas Jefferson, responded sharply:
Jefferson upbraided Genet for attempting to contact Congress at all, declaring that all of Genet’s transactions must occur with the Executive of the United States. Any communications between the President and Congress were none of his business, and he could not interfere. The “President must be left to judge for himself what matters his duty or the public good may require him to propose to the deliberations of Congress.”
and now they double down with a letter to Iran:
What these two constitutional provisions mean is that we will consider any agreement regarding your nuclear-weapons program that is not approved by the Congress as nothing more than an executive agreement between President Obama and Ayatollah Khamenei. The next president could revoke such an executive agreement with the stroke of a pen and future Congresses could modify the terms of the agreement at any time.
Basically Cotton and the others who signed the letter are telling other countries not to trust the US. Also, Iranian Foreign Minister Javad Zarif shows in a response to the letter that he is much more intelligent than Cotton:
Foreign Minister Zarif added that “I should bring one important point to the attention of the authors and that is, the world is not the United States, and the conduct of inter-state relations is governed by international law, and not by US domestic law. The authors may not fully understand that in international law, governments represent the entirety of their respective states, are responsible for the conduct of foreign affairs, are required to fulfil the obligations they undertake with other states and may not invoke their internal law as justification for failure to perform their international obligations.
The Iranian Foreign Minister added that “change of administration does not in any way relieve the next administration from international obligations undertaken by its predecessor in a possible agreement about Irans peaceful nuclear program.” He continued “I wish to enlighten the authors that if the next administration revokes any agreement with the stroke of a pen, as they boast, it will have simply committed a blatant violation of international law.”
He emphasized that if the current negotiation with P5+1 result in a Joint Comprehensive Plan of Action, it will not be a bilateral agreement between Iran and the US, but rather one that will be concluded with the participation of five other countries, including all permanent members of the Security Council, and will also be endorsed by a Security Council resolution.
Ah well, this is just your modern Republican Party at work.